2x2 vs 3x3 antenna (X220)

[FragrantHead]

The X220 currently makes you choose between getting a 2x2 screen (with Centrino 6205) and camera, vs. 3x3 screen (with Centrino 6300) and no camera. There must not be space for both the camera and the additional antennas of the 3x3.

How much difference does the 3x3 solution make to WiFi? How much of an improvement or what situations is it helpful in? Does it affect/improve mobile broadband reception as well?

[FragrantHead]

100 page views in a day or so. Guess I'm not the only one interested in the answer. Here's what I've found out so far.

The 6300 is codenamed Puma Peak and supports the 3x3 antennae for a theoretically maximum bandwidth of 450Mb/s using 3 channels simultaneously, if you have a compatible router.

While the 6200 was also codenamed Puma Peak, the 6205 is Taylor Peak. According to one forum post elsewhere, it is possibly a hardware revision to support the final Wireless-N standard, as opposed to the draft 2.0 standard, with possibly better 40Mhz something or other (channel bonding, interference rejection, I don't know). Don't know where that leaves the 6300, e.g. why there is no 6305. The 6200 and 6205 "only" support a maximum bandwidth of 300Mb/s. If you're using this for broadband access, it won't matter, since that's still an order of magnitude slower for most people.

It seems unclear whether you get better range, better signal strength at a given range or a more consistent signal with the 3x3, nor what sort of router you would need to achieve the same. Possibly that's not at all what this is about, but just the channel bonding (is that the term?) for potentially greater overall bandwidth with the right wireless-N AP.

[jeffm]

After reading the links below, I don't think the extra antenna will give you better range - just higher theoretical throughput:

http://www.intel.com/products/wireless/ ... /index.htm

http://www.intel.com/products/wireless/ ... /index.htm

[FragrantHead]

I'd skimmed those links before. Upon reading them again, I disagree with your assessment. I think the situation is as unclear as before. For the 6205 it says:

Delivers up to 300 Mbps and 2X greater range with 2 antennas for faster, more reliable wireless connectivity in more places ... [continued in note 1] ... based on the theoretical maximum enabled by 2x2 802.11n implementations with 2 spatial streams.

For the 6300 it says:

Delivers up to 450 Mbps and 2X greater range with 3 antennas for faster, more reliable wireless connectivity in more places ... [continued in note 2] ... up to 2X greater range enabled by 3x3 802.11n implementations with 3 spatial streams.

That's 2X greater range, relative to what? How can the 6205 achieve up to 2X greater range with 2 antennas when the 6300 only achieves the same with 3 spatial streams? I find the way this is phrased unfortunate. There is probably some technical basis to it, but it seems like the marketing department has just copied and pasted those descriptions with slight changes. They don't go into where the 6205 falls relative to the 6300 in the 1X up to 2X distance range achieved on average. However they both talk about range and "faster, more reliable wireless connectivity in more places", not just the theoretical maximum bandwidth. Do they both achieve the same proficiency relative to the same baseline? How can you tell when they don't even say what the baseline is. The lack of precision turns what could have been useful information into meaningless marketing drivel.

[GomJabbar]

In regards to 2x2 vs 3x3, your last post seems clear. Same distance but better thoroughput for the 3x3 - 300 Mbps vs 450 Mbps.

[FragrantHead]

If I was a sane person, I'd probably agree with you. However, if I had to roll out loads of these for a customer and I had to make a technical decision between 6205 and 6300 based on factors other than the maximum bandwidth, I would have questions. If 2 antennas improve range and reliability, then will 3 antennas improve it more or are Wireless-N implementations such that this doesn't really happen? To me those Intel links aren't precise enough to answer that. It just seems like such an obvious question.

Also, what do they mean by spatial streams? Are we talking about waves oriented in the 3 dimensions here? Because if that was the case the only way you could achieve antennas oriented at all right angles to each other would be to put 2 in the screen and 1 in the body of the notebook, with the screen standing upright.

[visionviper]

http://s2n.merunetworks.com/2009/08/wha ... 11n-works/

Read that and see if that helps your question.

Range doesn't change with the number of antennas. There are two things that affect range with antennas: Power and antenna design. Adding more of the same antennas will not improve range (unless we are talking access points, but then the antennas are placed in different physical locations). What it will do is provide better throughput over the same range and possibly better connection quality.

[FragrantHead]

Interesting link. As ever reality is even more complex than you first think.

[bill bolton]

I have an X200 with 2x2 antenna and a Intel 5300 card installed. I also have aT400 with the same card but a 3x3 antenna.

In our upstairs main bedroom, with a floor and a couple of walls between my Linksys e4200 router and the Thinkpad, the X200 won't sustain a 802.11n connection but the T400 will.

That does seem to provide some prima facie indication for Intel cards that a 3x3 antenna will support 802.11n operation at greater range than a 2x2

Cheers,

Bill B.

[FragrantHead]

Aha!

[cyberboris]

I suppose the T400 does a better job concerning the range because it has larger antennas within it's 14 inches frame.

I have a T410s with Intel 6300 3x3 and while it connects at 217Mbps (sometimes 450Mbps) my other Thinkpads with 11, 12, 13.3" frames never achieve more than 108Mbps and usually only 54Mbps. All are 2x2 antennas (or less?), but i know for sure that my T410s connects at higher speeds.

Conclusion : size does matter (size of the antennas of course !).

For reference I own X41, X100e, Reserve Edition (X61s i believe), X200s, X301, T23, T43, etc.

English is not my native language, i hope i was clear enough

[bill bolton]

I suppose the T400 does a better job concerning the range because it has larger antennas within it's 14 inches frame.

I suppose you have no idea about the way that antennas work in the GHz bands.

my other Thinkpads with 11, 12, 13.3" frames....

Unless they all have the exact same card installed as in your T410s, its not a valid comparision for that reason alone.

Cheers,

Bill B.

[FragrantHead]

What you mean to say is that the optimum length or other physical characteristics of the antenna depend on the frequency (range) it's designed for, right? Longer is not automatically better. The antenna stubs that stick out a WiFi rounter are all short enough to fit in even an 11" laptop and are presumably optimum length for 2.4GHz WiFi, right?